The oxidation of NO to NO2 was investigated on Co-Ce-Zr solid solutions prepared by the sol-gel method. An improvement of the catalytic activities of the samples was observed for Co-contained catalysts compared to Ce-Zr solid solution. The ZCCo(0.36) catalyst exhibited more than 50 % NO conversion rate in the temperature range from 250 to 350 A degrees C. The chemico-physical properties of catalysts were characterized by XRD, Raman spectroscopy, BET, XPS and NO-TPD. The results indicated that the introduction of cobalt into the lattice of Ce-Zr solid solution increased the amount of Ce3+ and facilitated the oxygen mobility. The features may be responsible for the improving of catalytic activities of Co-Ce-Zr metal-oxides for NO oxidation.